method in
their comings and goings, and this method may in turn be definable. It
will be a new sort of constant illustrated in the flux; and this we call
a law. If events could be reduced to a number of constant forms moving
in a constant medium according to a constant law, a maximum of constancy
would be introduced into the flux, which would thereby be proved to be
mechanical.

The form of events, abstracted from their material presence, becomes a
general mould to which we tend to assimilate new observations. Whatever
in particular instances may contravene the accredited rule, we attribute
without a qualm to unknown variations in the circumstances, thus saving
our faith in order at all hazards and appealing to investigation to
justify the same. Only when another rule suggests itself which leaves a
smaller margin unaccounted for in the phenomena do we give up our first
generalisation. Not even the rudest superstition can be criticised or
dislodged scientifically save by another general rule, more exact and
trustworthy than the superstition. The scepticism which comes from
distrust of abstraction and disgust with reckoning of any sort is not a
scientific force; it is an intellectual weakness.

Generalities are indeed essential to understanding, which is apt to
impose them hastily upon particulars. Confirmation is not needed to
create prejudice. It suffices that a vivid impression should once have
cut its way into the mind and settled there in a fertile soil; it will
entwine itself at once with its chance neighbours and these adventitious
relations will pass henceforth for a part of the fact. Repetition,
however, is a good means of making or keeping impressions vivid and
almost the only means of keeping them unchanged. Prejudices, however
refractory to new evidence, evolve inwardly of themselves. The mental
soil in which they lie is in a continual ferment and their very vitality
will extend their scope and change their application. Generalisations,
therefore, when based on a single instance, will soon forget it and
shift their ground, as unchecked words shift their meaning. But when a
phenomenon actually recurs the generalisations founded on it are
reinforced and kept identical, and prejudices so sustained by events
make man's knowledge of nature.

[Sidenote: Their discovery makes the flux calculable.]

Natural science consists of general ideas which look for verification in
events, and which find it. The particular i